The Dream Plague is an unusual psionic effect that affects a large swathe of psions in a given area. Only psionically capable creatures are susceptible to the Dream Plague; although there is a detectable presence of psionically active microbiotes present in the radius of the Plague, the source has not been determined. Only one Plague can be in effect at any given time, and a Plague seems to occur somewhere in the galaxy at least once every three days.

The Dream Plague saps psionic energy from all living things within a radius of up to 200 miles. An extremely faint, deep blue glow is present; it can only really be observed at long distances, as it is hard to see at close ranges. Individuals can be protected from the Dream Plague in air-tight rooms, but otherwise the Dream Plague can spread through buildings with ease in even the smallest openings. Any psionically active object touching the Dream Plague's body of microbes will be sapped, with the energy coursing through the air in ethereal strings, usually from around the brain of a living creature or the psionic storage of psionic devices. The energy can not be tracked; it billows out into the entire cloud of microbes, spread too thin to be reclaimed.

The Dream Plague's most immediate effects are lethargy in psionic creatures and loss of functionality in psionic devices; despite the lack of an apparent intelligent origin, the Dream Plague has never been observed to sap enough energy from any living thing to kill it. It can, however, completely absorb the stored energy of psionic devices, rendering them useless. However, the Dream Plague is named for its anomalous effects on the dreams of psions; psions will sleep poorly and briefly when the Dream Plague is present despite its drowsiness-inducing effects, but when they do sleep, they will dream of the same scene. Experimentation on dreaming subjects shows that their dreams are in sync, and seem to be the result of mind-affecting psionics being fed into, rather than through, the Plague cloud.

These dreams vary; often times, there are no dreams whatsoever, but those who do dream not only have a chance to witness everyone else currently affected by the Cloud in their dream even if they had never seen such individuals, but also will encounter elements regular to the dreams of entirely separate individuals, including memories of others' lives, as if all those currently sleeping were having their dreams joined.

Analysis of the Plague's microbes has been difficult and inconclusive; they do not naturally have any ability to produce mind-affecting psionics and seem to be a highly developed 'psionic vector', like those used in psionic weapons and tools which are intended to help carry and maintain shaped psionic charges through the air. Where the energy taken goes is unknown, as the microbes themselves could not possibly consume even a small fraction of the amount they transfer. The transitory nature of the Plague across massive distances, despite its ability to only operate within one location at any given time, indicates that it is likely designed and deployed intentionally by an unknown operator.